Japan develops simpler organic semiconductors

RESEARCHERS in Japan have developed a simplified method to form various organic semiconductors, in a breakthrough that could lead to the development of more energy efficient organic electronic devices and luminescent materials, according to a study published in the Journal of the American Chemical Society.

The method involves heating mono-functionalized polycyclic aromatic hydrocarbons (PAHs) with sulfur to create a common type of organic semiconductor called a “thiophene-fused PAH.”

A semiconductor is a non-metallic material that has the ability to conduct electricity, either due to temperature or the presence of some kind of impurities. Semiconductors like silicon are essential components in electronic devices.

Thiophene is molecule containing four carbon atoms and a sulfur atom. Thiophene-fused PAHs are known to be one of the most common organic semiconductors and are used in various electronic materials, such as in transistors, organic thin-film solar cells, organic electro-luminescent diodes and electronic devices.

A team led by Assistant Professor Yasutomo Segawa and Professor Kenichiro Itami of the Japan Science and Technology Agency-ERATO succeeded in developing a simple and effective method for the formation of various thiophene-fused PAHs.

According to the scientists, the reactions can be carried out on a multigram scale and can be conducted in a one-pot, two-step reaction sequence starting from an unfunctionalized PAH, a process that could be scaled up with relative ease.

“We coincidentally discovered this reaction when we were testing different chemical reactions to synthesize a new molecule for the Itami ERATO project,” said Segawa.

The researchers related how they were surprised that the relatively simple process had not been previously discovered. “The most difficult part of this research was to clarify the novelty of this reaction. We put in a significant amount of effort to investigate previous reports, including textbooks from more than 50 years ago as well as various internet sources, to make sure that our reaction conditions had not been disclosed before,” Segawa explained.